Experimental Shock Research Articles

Generalized Shwartzman Reaction as an Experimental Endotoxin Shock Model: Role of Intermediate T Cell Receptor-Expressing Innate T Lymphocytes in its Pathogenesis

Endotoxin and its induced exaggerative responses of proinflammatory cytokines such as Tumor Necrosis Factor (TNF) cause human septic shock. The generalized Shwartzman reaction is considered as an experimental endotoxin shock model and its representative features are high lethality and hypersensitive inflammatory response to endotoxin, in particular excessive TNF production. The generalized Shwartzman reaction can be induced by Interleukin (IL)-12 priming and subsequent endotoxin challenge. IL-12 primes the intermediate T cell receptor (TCR)-expressing innate T lymphocytes (natural killer T cells and CD8+CD122+ T cells in mice, CD56+ T cells and CD57+ T cells in human) to produce IFN-γ, which in turn preconditions macrophages to produce a large amount of TNF in response to endotoxin. These intermediate TCR innate T lymphocytes play a pivotal role for the occurrence of this generalized Shwartzman reaction. Some of the intermediate TCR-expressing innate T lymphocytes (CD8+CD122+ T cells in mice and CD57+ T cells in human), which are considered as extrathymically developed T lymphocytes, are increased with age and closely involved in age-dependent augmentation of murine generalized Shwartzman reaction and human Shwartzman-like reaction, which may reflect an exacerbation of septic shock in elderly. However, these intermediate TCR innate T lymphocytes normally augment host immunity against malignant tumors and refractory bacterial infections, which are critical threats in aged hosts. Thus, intermediate TCR-expressing innate T lymphocytes may be a double-edged sword on the host defense, especially elderly hosts.

The Role of Nitric Oxide in the Efficacy of Adenosine, Lidocaine, and Magnesium Treatment for Experimental Hemorrhagic Shock in Rats

BackgroundNitric oxide (NO) plays multiple roles regulating the central nervous, cardiovascular, and immune systems.ObjectiveOur aim was to investigate the role of NO in the efficacy of hypertonic saline (7.5% sodium chloride [NaCl]) adenosine, lidocaine, and magnesium (ALM) to improve mean arterial pressure (MAP) and heart rate following hemorrhagic shock.MethodsOne hundred one male Sprague-Dawley rats (mean [SD] weight = 425 [6] g) were randomly assigned to 20 groups (groups of 4–8 rats each). Hemorrhagic shock (MAP < 40 mm Hg) was induced by 20-minute pressure-controlled bleeding (∼40% blood volume), and the animal was left in shock (MAP = 35-40 mm Hg) for 60 minutes. The NO synthase (NOS) inhibitor L-NAME was administered with a 0.3-mL bolus of different combinations of 7.5% NaCl ALM active ingredients and hemodynamic parameters were monitored for 60 minutes. A number of specific NOS and NO inhibitors were tested.ResultsWe found that 7.5% NaCl ALM corrected MAP after hemorrhagic shock. In contrast, the addition of L-NAME to 7.5% NaCl ALM led to a rapid fall in MAP, sustained ventricular arrhythmias, and 100% mortality. Saline controls receiving 7.5% NaCl with NG-nitro-l-arginine methyl ester (L-NAME) showed improved MAP with no deaths. None of the specific NOS and NO inhibitors mimicked L-NAME's effect on ALM. The addition of inducible NOS inhibitor 1400W to 7.5% NaCl ALM failed to resuscitate, whereas the NO scavenger PTIO and the PI3K inhibitor wortmannin reduced MAP recovery during 60-minute resuscitation.ConclusionsThe ability of 7.5% NaCl ALM to resuscitate appears to be linked to 1 or more NO-producing pathways. Nonspecific NOS inhibition with L-NAME blocked ALM resuscitation and led to cardiovascular collapse. More studies are required to examine NO site-specific contributions to ALM resuscitation. (Curr Ther Res Clin Exp. 2022; 82:XXX–XXX)

Equation-of-state measurements for polystyrene under high presure driven by HEAVEN-I laser facility

The equation of state (EOS) for CH material used as an ablator layer at high pressure is important in the study of implosion dynamics and target design for inertial confinement fusion (ICF). At present, most of EOS data are on the Hugoniot line under shock compression. The EOS data below Hugoniot line need further studying for low-entropy pre- compression. In the present article, the EOS of polystyrene is established under quasi-isentropic compression driven by HEAVEN-I KrF laser facility with a long rising edge (~20 ns). The shock dynamic behaviors of three kinds of CH targets are simulated, which are 100 μm CH planar target, Al-coated CH planar target (10 μm Al, 50 or 150 μm CH), and flyer-impact target composed of flyer (Al-coated CH), 100 μm vacuum layer, and 100 μm CH layer. The planar targets and flyer-impact targets with different thickness are irradiated by six-focused laser beams with total energy of 50–100J, and the free surface velocity and wave average transit velocity are measured by side-on shadowgraph technique. The simulation results indicate that the initial loading process is quasi-isentropic compression process, and then evolves into a weak shock compression process for the CH planar target in the rising edge stage. Comparing with the CH planar target, the reflected rarefaction waves from the Al-CH interface of Al-coated CH target can suppress the enhancement of compression wave, and delay the formation of shock wave when laser directly irradiates the Al layer. The shock pressure of the CH target layer (the third layer) is significantly higher than those of the former two targets in the flyer-impact target. However, the chasing rarefaction wave can unload the compression state incompletely and reduce the pressure when the CH target layer is much thicker than Al layer. The final pressure is about 15 GPa in the CH planar target, while the final pressure is about 30 GPa in flyer-impact target: both of them are less than the pressure threshold of opacity change for the transparent polystyrene. The quasi-isentropic dynamical process is difficult to measure by the velocity interferometer system for any reflector technique. The experimental results show that the average wave transit velocity is significantly less than the final shock velocity derived from the free surface velocities in the CH and Al-coated CH planar target side-on shadow experiments. They indicate that the compression wave enhancement and quasi-isentropic compression process occur in the propagation of wave front. The shock pressure is about 12 GPa in the CH planar target, and about 34 GPa under shock load in the flyer-impact target. The experimental data and shock dynamic processes are basically consistent with the simulation results.

Experimental validation of shock propagation through a foam with engineered macro-pores

The engineered macro-pore foam provides a new way to study thermonuclear burn physics by utilizing capsules containing deuterated (D) foam and filling tritium (T) gas in the engineered macro-pores. The implosion of a thermonuclear capsule filled with an engineered macro-pore foam will be complex due to the interaction of a shock wave with the engineered macro-pores. It is our goal to quantify how substantially complex foam structures affect the shape of shock and bulk shock speed. A cylinder-shape shock tube experiment has been designed and performed at the Omega Laser Facility. In order to examine how a foam structure will affect shock propagation, we performed several tests varying (1) engineered macro-pore size, (2) average foam density, and (3) with/without neopentane (C5H12) gas. X-ray radiographic data indicate that shock speed through engineered macro-pore foams depends strongly on average foam density and less on pore size. Experimental shock propagation data helped guide two numerical simulation approaches: (1) a 2D simulation with homogenizing foams rather than explicitly simulating engineered macro-pores and (2) a 2D toroidal-pore approximation adopting a toroidal-tube geometry to model engineered macro-pores.

Calibration of reactive burn and Jones-Wilkins-Lee parameters for simulations of a detonation-driven flow experiment with uncertainty quantification

Uncertainty-quantification-driven simulations of an explosive experiment are performed to minimize the flow prediction error in the PBXN-5 detonation products and air flow. The global sensitivity response of JWL model parameters based on simulation transverse shock position is given by main sensitivity index over time. The calibration of explosive products model parameters based on experimental shock position data produces good agreement between simulation and experimental results.

Retrospective Analysis and Current State of Experimental Models of Blast-induced Trauma

Combat pathology, particularly mine-blast injury is the main cause of military casualties. In our country, as a factor of destabilization, are widely used terrorist attacks using explosive devices of different capacities. Blast injury over 60% is cause of military casualties during armed conflicts. It is known that the condition for the formation of air-shock wave is creating waves of pressure, which is distributed at supersonic speed as possible with pulsed gas explosion and expansion of compression ambient air. The brain, chest, abdomen, and bladder are the most sensitive parts of the human body to blast. But the pathogenesis, diagnosis, treatment and rehabilitation of post-traumatic explosion-induced disorders, namely, neurodegenerative complications psychosomatic, cognitive impairment, currently not fully understood and are not clear enough for an adequate therapy. The purpose of the study was to analyze the advantages and disadvantages of experimental models of blast-induced injury and to improve method and compressed air-driven shock tube. Material and methods. We used the following methods: analysis and evaluation of experimental models of explosion-induced injury by scientific publications, monographs and invention obtained in stages patent information search in the library collection of the State institution "Dnipropetrovsk Medical Academy of the Ministry of Health of Ukraine" (October 2019), a retrospective search of the literature database PubMed (February 2020). Results and discussion. A retrospective analysis of the number of literary sources on the experimental reproduction of explosive trauma has shown a high interest of a large circle of scientists in the last decade. A qualitative study of scientific publications has shown a wide range of physical characteristics of an experimental shock wave, methods and devices for simulating an explosive injury. The absence of a standardized model of explosive injury with characteristics as close as possible to real circumstances creates conditions for the implementation of our own proposals. Conclusion. This work presents a tested modified experimental model for reproducing an air shock wave under laboratory conditions, which makes it possible to study the features of the course of an explosive injury of various organs and organ systems at various periods after injury

Measuring the shock Hugoniot data of liquid nitrogen using a cryogenic system for shock compression

The study of homonuclear diatomic molecules under high pressure and high temperature is a fundamental problem of condensed matter physics. In this research work, a cryogenic target (CT) was built to liquefy the gas and execute shock compression. The characteristics of the CT and the diagnostic system are explained in detail. We performed a shock compression of liquid nitrogen by using a two-stage light-gas gun at pressures up to 93 GPa (0.93 Mbar). Impactor velocities were measured with the magnetic velocimetry system, with a precision of 0.2%. The optical waveforms were recorded with the Doppler pin system, then further fast Fourier transform obtained velocity profiles in the sample. The measured velocity profiles were used to identify optical reflectance and obtain first-shock velocities, independent of the sample thickness above dissociative pressure (&amp;gt;30 GPa). The measured shock velocities had an uncertainty of less than 1%. First particle velocities were calculated by impedance matching, and the second velocities were directly calculated from the velocity profiles in an LiF anvil. The experimental shock Hugoniot results were observed to be consistent with those of the previous work. However, the principal Hugoniot softened above 27 GPa, and the uncertainties in the first and second-shock volumes were less than 0.7% and 3%, respectively.

Procalcitonin Exerts a Mediator Role in Septic Shock Through the Calcitonin Gene-Related Peptide Receptor.

Clinically, procalcitonin represents the most widely used biomarker of sepsis worldwide with unclear pathophysiologic significance to date. Pharmacologically, procalcitonin was shown to signal through both calcitonin receptor and calcitonin gene-related peptide receptor in vitro, yet the identity of its biologically relevant receptor remains unknown. Prospective randomized animal investigations and in vitro human blood studies. Research laboratory of a university hospital. C57BL/6J mice and patients with post-traumatic sepsis. Procalcitonin-deficient mice were used to decipher a potential mediator role in experimental septic shock and identify the relevant receptor for procalcitonin. Cecal ligation and puncture and endotoxemia models were employed to investigate septic shock. Disease progression was evaluated through survival analysis, histology, proteome profiling, gene expression, and flow cytometry. Mechanistic studies were performed with cultured macrophages, dendritic cells, and gamma delta T cells. Main findings were confirmed in serum samples of patients with post-traumatic sepsis. Procalcitonin-deficient mice are protected from septic shock and show decreased pulmonary inflammation. Mechanistically, procalcitonin potentiates proinflammatory cytokine expression in innate immune cells, required for interleukin-17A expression in gamma delta T cells. In patients with post-traumatic sepsis, procalcitonin positively correlates with systemic interleukin-17A levels. In mice with endotoxemia, immunoneutralization of interleukin-17A inhibits the deleterious effect of procalcitonin on disease outcome. Although calcitonin receptor expression is irrelevant for disease progression, the nonpeptide calcitonin gene-related peptide receptor antagonist olcegepant, a prototype of currently introduced antimigraine drugs, inhibits procalcitonin signaling and increases survival time in septic shock. Our experimental data suggest that procalcitonin exerts a moderate but harmful effect on disease progression in experimental septic shock. In addition, the study points towards the calcitonin gene-related peptide receptor as relevant for procalcitonin signaling and suggests a potential therapeutic application for calcitonin gene-related peptide receptor inhibitors in sepsis, which warrants further clinical investigation.

Regional venous\u2013arterial CO2 to arterial\u2013venous O2 content difference ratio in experimental circulatory shock and hypoxia

BackgroundVenous–arterial carbon dioxide (CO2) to arterial–venous oxygen (O2) content difference ratio (Cv-aCO2/Ca-vO2) > 1 is supposed to be both sensitive and specific for anaerobic metabolism. What regional hemodynamic and metabolic parameters determine the ratio has not been clarified.ObjectivesTo address determinants of systemic and renal, spleen, gut and liver Cv-aCO2/Ca-vO2.MethodsPost hoc analysis of original data from published experimental studies aimed to address effects of different fluid resuscitation strategies on oxygen transport, lactate metabolism and organ dysfunction in fecal peritonitis and endotoxin infusion, and from animals in cardiac tamponade or hypoxic hypoxia. Systemic and regional hemodynamics, blood flow, lactate uptake, carbon dioxide and oxygen-derived variables were determined. Generalized estimating equations (GEE) were fit to assess contributors to systemic and regional Cv-aCO2/Ca-vO2.ResultsMedian (range) of pooled systemic Cv-aCO2/Ca-vO2 in 64 pigs was 1.02 (0.02 to 3.84). While parameters reflecting regional lactate exchange were variably associated with the respective regional Cv-aCO2/Ca-vO2 ratios, only regional ratios were independently correlated with systemic ratio: renal Cv-aCO2 /Ca-vO2 (β = 0.148, 95% CI 0.062 to 0.234; p = 0.001), spleen Cv-aCO2/Ca-vO2 (β = 0.065, 95% CI 0.002 to 0.127; p = 0.042), gut Cv-aCO2/Ca-vO2 (β = 0.117, 95% CI 0.025 to 0.209; p = 0.013), liver Cv-aCO2/Ca-vO2 (β = − 0.159, 95% CI − 0.297 to − 0.022; p = 0.023), hepatosplanchnic Cv-aCO2/Ca-vO2 (β = 0.495, 95% CI 0.205 to 0.786; p = 0.001).ConclusionIn a mixed set of animals in different shock forms or during hypoxic injury, hepatosplanchnic Cv-aCO2/Ca-vO2 ratio had the strongest independent association with systemic Cv-aCO2/Ca-vO2, while no independent association was demonstrated for lactate or hemodynamic variables.

Dynamic Arterial Elastance During Experimental Endotoxic Septic Shock: A Potential Marker of Cardiovascular Efficiency.

Dynamic arterial elastance (Eadyn), the ratio between pulse pressure variation (PPV) and stroke volume variation (SVV), has been suggested as a dynamic parameter relating pressure and flow. We aimed to determine the effects of endotoxic septic shock and hemodynamic resuscitation on Eadyn in an experimental study in 18 New Zealand rabbits. Animals received placebo (SHAM, n = 6) or intravenous lipopolysaccharide (E. Coli 055:B5, 1 mg⋅kg–1) with or without (EDX-R, n = 6; EDX, n = 6) hemodynamic resuscitation (fluid bolus of 20 ml⋅kg–1 and norepinephrine for restoring mean arterial pressure). Continuous arterial pressure and aortic blood flow measurements were obtained simultaneously. Cardiovascular efficiency was evaluated by the oscillatory power fraction [%Osc: oscillatory work/left ventricular (LV) total work] and the energy efficiency ratio (EER = LV total work/cardiac output). Eadyn increased in septic animals (from 0.73 to 1.70; p = 0.012) and dropped after hemodynamic resuscitation. Eadyn was related with the %Osc and EER [estimates: −0.101 (−0.137 to −0.064) and −9.494 (−11.964 to −7.024); p < 0.001, respectively]. So, the higher the Eadyn, the better the cardiovascular efficiency (lower %Osc and EER). Sepsis resulted in a reduced %Osc and EER, reflecting a better cardiovascular efficiency that was tracked by Eadyn. Eadyn could be a potential index of cardiovascular efficiency during septic shock.

HDFx, a Natural Biologic is Associated with Elevated DNA Methylation, Reduced DNA Oxidation and Telomerases Down-regulation in Macrophages and Monocytes Derived from Surviving Animals Subjected to Experimental Shock and Burns: Males vs. Females and Relation to Resistance Against Bacterial &amp; Viral Infections

Circulatory shock and burns are significant and sustained states of hypoperfusion and lead to decreases in circulating blood volume combined with decreased tissue and organ oxygenation. This hypoperfusion state often causes sepsis resulting in a state of “multiple organ failure” [1-3]. Due to severe body burns, battle field casualties are most susceptible to the latter resulting in numerous loss of lives.

HDFx, a Natural Biologic is Associated with Elevated DNA Methylation, Reduced DNA Oxidation and Telomerases Down-regulation in Macrophages and Monocytes Derived from Surviving Animals Subjected to Experimental Shock and Burns: Males vs. Females and Relation to Resistance Against Bacterial &amp; Viral Infections

Circulatory shock and burns are significant and sustained states of hypoperfusion and lead to decreases in circulating blood volume combined with decreased tissue and organ oxygenation. This hypoperfusion state often causes sepsis resulting in a state of “multiple organ failure” [1-3]. Due to severe body burns, battle field casualties are most susceptible to the latter resulting in numerous loss of lives.

Therapeutic Hypothermia Improves Long-Term Survival and Blunts Inflammation in Rats During Resuscitation of Hemorrhagic Shock.

We tested the hypothesis that therapeutic hypothermia (TH) improves survival and blunts inflammation in rats undergoing experimental hemorrhagic shock. Rats were randomized to TH (n = 16) or normothermia (n = 15). Hemorrhagic shock was induced by withdrawing blood to a fixed mean blood pressure (MBP) of 30 mmHg for 30 minutes followed by reinfusion of shed blood for the next 30 minutes. TH (target 32°C) was started at 5 minutes after MBP reached 30 mmHg and was maintained throughout blood volume resuscitation. In the normothermic control group, body temperature was maintained at 37°C during the procedure. Rats were allowed to recover for 6 weeks. TH significantly improved survival: 4 of 15 (26.7%) rats in the normothermic group and 11 of 16 (68.8%; p = 0.032) rats in the TH group survived 6 weeks. Recovery of MBP during the resuscitation phase was significantly improved and left ventricular fractional shortening was markedly increased in the TH group compared with the normothermic group. Brain infarction was observed in 3 of 4 surviving rats (75%) in normothermic group, and in only 1 of the 11 surviving rats (9%) in TH group. The neutrophil-to-lymphocyte ratio was lower in TH group (0.20 ± 0.02) compared with the normothermic group (0.32 ± 0.03; p = 0.003). TH influenced the levels of blood gases and blood counts, favoring hypothermia over control. TH significantly improved long-term survival and blunted the inflammatory response in experimental hemorrhagic shock.

Therapeutic interventions to restore microcirculatory perfusion following experimental hemorrhagic shock and fluid resuscitation: A systematic review.

ObjectiveMicrocirculatory perfusion disturbances following hemorrhagic shock and fluid resuscitation contribute to multiple organ dysfunction and mortality. Standard fluid resuscitation is insufficient to restore microcirculatory perfusion; however, additional therapies are lacking. We conducted a systematic search to provide an overview of potential non‐fluid‐based therapeutic interventions to restore microcirculatory perfusion following hemorrhagic shock.MethodsA structured search of PubMed, EMBASE, and Cochrane Library was performed in March 2020. Animal studies needed to report at least one parameter of microcirculatory flow (perfusion, red blood cell velocity, functional capillary density).ResultsThe search identified 1269 records of which 48 fulfilled all eligibility criteria. In total, 62 drugs were tested of which 29 were able to restore microcirculatory perfusion. Particularly, complement inhibitors (75% of drugs tested successfully restored blood flow), endothelial barrier modulators (100% successful), antioxidants (66% successful), drugs targeting cell metabolism (83% successful), and sex hormones (75% successful) restored microcirculatory perfusion. Other drugs consisted of attenuation of inflammation (100% not successful), vasoactive agents (68% not successful), and steroid hormones (75% not successful).ConclusionImproving mitochondrial function, inhibition of complement inhibition, and reducing microvascular leakage via restoration of endothelial barrier function seem beneficial to restore microcirculatory perfusion following hemorrhagic shock and fluid resuscitation.

Vibrational relaxation time measurements in shock-heated oxygen and air from 2000 K to 9000 K using ultraviolet laser absorption

Vibrational relaxation times of oxygen (O2) were measured behind reflected shocks in shock-tube experiments with O2 and nitrogen (N2) collision partners. To determine relaxation times, a tunable ultraviolet laser absorption diagnostic probed time-histories involving the fourth (v″ = 4), fifth (v″ = 5), and sixth (v″ = 6) vibrational levels of the ground electronic state of O2. Taking the ratio of two absorbance time-histories involving different vibrational levels yielded vibrational temperature time-histories that were fit to isolate the relevant vibrational relaxation times. Pure O2 experiments were used to isolate the vibration–translation (VT) relaxation time of O2 with O2. Results for τVTO2–O2 agree with the Millikan and White correlation at temperatures below 4000 K. However, high-temperature data deviate from the Millikan and White correlation, exhibiting a reduced temperature dependence—an observation that remains consistent with previous experimental studies. Additional experiments in 10% and 21% O2 in N2 mixtures were used to isolate both the VT and vibration–vibration (VV) relaxation times of O2 with N2. The data for τVTO2–N2 exceed the Millikan and White correlation by 70% but show reasonable agreement with previous data below 5000 K. High-temperature results again show a reduced temperature dependence, but this study shows longer relaxation times than the previous work. The data for τVVO2–N2 exceed the semi-empirical relation developed by Berend et al. [“Vibration-vibration energy exchange in N2 with O2 and HCl collision partners,” J. Chem. Phys. 57, 3601–3604 (1972)] by 70% but overlap with previous measurements. Due to insensitivity of the chemical system to VV transfer at high temperatures, results for τVVO2–N2 were only measured below 6000 K.

Recombinant short TNF-BD protein from smallpox virus is pharmacologically active in an experimental septic shock model

Фактор некроза опухолей (TNF) – один из основных цитокинов, медиаторов иммунной системы, обеспечивающих защиту организма человека от вирусных инфекций. В процессе эволюции антропогенный вирус натуральной оспы (Variola virus, VARV) освоил эффективные механизмы преодоления иммунологических барьеров человека, кодируя в своем геноме белки, способные взаимодействовать с рецепторами цитокинов организма-хозяина, блокируя таким образом их активность. В частности, ген G2R этого вируса кодирует белок CrmB, который эффективно связывает TNF человека и мышей. При этом данный белок является двухдоменным и наряду с TNF-связывающим N-концевым доменом содержит С-концевой хемокин-связывающий домен. При использовании методологии молекулярного клонирования нами ранее получен рекомбинантный бакуловирус, продуцирующий в клетках насекомых рекомбинантный белок CrmB вируса натуральной оспы (VARV-CrmB), и показан его TNF-нейтрализующий потенциал в различных тестах in vitro и in vivo. С целью снижения иммуногенности этого вирусного белка при его многократном введении для терапии хронических воспалительных заболеваний получена рекомбинантная плазмида, направляющая в клетках Escherichia coli биосинтез укороченного однодоменного TNF-связывающего (TNF-BD) белка VARV. Методом металл-хелатной аффинной хроматографии из клеток выделен рекомбинантный белок TNF-BD. Терапевтический потенциал белка TNF-BD изучен в экспериментальной модели септического шока, индуцированного в организме мышей введением бактериального липополисахарида (ЛПС). После индукции септического шока животным вводили разные дозы рекомбинантного белка TNF-BD и регистрировали их гибель в течение 7 сут. Все мыши, не получавшие препарат белка TNF-BD после инъекции ЛПС, погибли через 3 сут, а в группах животных, которым вводили TNF-BD, в зависимости от дозы этого белка выжили 30, 40 или 60 % мышей. Результаты исследования демонстрируют наличие специфической фармакологической активности у рекомбинантного белка TNF-BD, синтезированного в бактериальных клетках, в мышиной модели ЛПС-индуцированного септического шока.

Reevaluation of the reaction rate of H + O2 (+M) = HO2 (+M) at elevated pressures

The rate coefficients for H + O2 (+M) = HO2 (+M) at high-pressure conditions were re-evaluated using the reported experimental shock tube data of Davidson et al. (1996), Bates et al. (2001), Shao et al. (2019) and Choudhary et al. (2019), and based on an updated mechanism of Hong et al. (2011). The major updates of the Hong et al. Mechanism compared to the originally used GRI-Mech in the works of Davidson et al. (1996) and Bates et al. (2001) were the interfering reactions of H + O2, H + HO2 and OH + HO2 as well as NOx-related reactions. After applying the updates of the elementary reaction kinetics, the revised rates of H + O2 (+M) = HO2 (+M) for Davidson et al. (1996) and Bates et al. (2001) showed improved agreement with each other, and consequently led to a more reliable Troe formula of H + O2 (+M) = HO2 (+M) with M = Ar and N2 covering the pressure range of 1–150 bar and temperature range of 300–1800 K. The new Troe formula is expected to facilitate kinetic model development and high-pressure combustion studies.

In canine bacterial pneumonia circulating granulocyte counts determine outcome from donor cells.

In experimental canine septic shock, depressed circulating granulocyte counts were associated with a poor outcome and increasing counts with prophylactic granulocyte colony-stimulating factor (G-CSF) improved outcome. Therapeutic G-CSF, in contrast, did not improve circulating counts or outcome, and therefore investigation was undertaken to determine whether transfusing granulocytes therapeutically would improve outcome. Twenty-eight purpose-bred beagles underwent an intrabronchial Staphylococcus aureus challenge and 4 hours later were randomly assigned to granulocyte (40-100 × 109 cells) or plasma transfusion. Granulocyte transfusion significantly expanded the low circulating counts for hours compared to septic controls but was not associated with significant mortality benefit (1/14, 7% vs. 2/14, 14%, respectively; p = 0.29). Septic animals with higher granulocyte count at 4 hours (median [interquartile range] of 3.81 3.39-5.05] vs. 1.77 [1.25-2.50]) had significantly increased survival independent of whether they were transfused with granulocytes. In a subgroup analysis, animals with higher circulating granulocyte counts receiving donor granulocytes had worsened lung injury compared to septic controls. Conversely, donor granulocytes decreased lung injury in septic animals with lower counts. During bacterial pneumonia, circulating counts predict the outcome of transfusing granulocytes. With low but normal counts, transfusing granulocytes does not improve survival and injures the lung, whereas for animals with very low counts, but not absolute neutropenia, granulocyte transfusion improves lung function.

Effects of hypertonic saline replacement on colonic anastomosis in experimental hemorrhagic shock model in rats.

Inadequate intestinal perfusion resulting from hemorrhagic shock negatively affects wound healing. In this experimental study, we aimed to evaluate the effects of resuscitation with hypertonic saline on colonic anastomosis in rats with controlled hemorrhagic shock. A total of 24 male Wistar albino rats weighing between 200 and 250 g were used in this study. The rats were divided into four groups as: Control, hypotonic, isotonic, and hypertonic. Median laparotomy, colon resection, and colocolonic anastomosis were performed to the rats in the control group. After creating controlled hemorrhagic shock to rats in other three groups, resuscitation was achieved with hypotonic, isotonic, and hypertonic saline. After resuscitation, median laparotomy, colon resection, and colocolonic anastomosis were performed on rats in these three groups. On the 5th post-operative day, a median laparotomy was applied to the rats in all groups and anastomosis lines were evaluated. Anastomotic bursting pressure, tissue hydroxyproline level, and tissue fibrosis degree were compared between the groups. There was no statistically significant difference between the groups in terms of anastomotic bursting pressure, tissue hydroxyproline level, and tissue fibrosis degree (respectively; p=0.320, p=0.537, p>0.05). In rats with controlled hemorrhagic shock, resuscitation with hypertonic saline does not differ significantly from isotonic or hypotonic saline in terms of healing of colonic anastomosis.

A pressure- or velocity-dependent acceleration rate law for the shock-to-detonation transition process in PBX 9502 high explosive

Shock-to-detonation transition profiles of PBX 9502 explosive are analyzed to develop a rate law for shock acceleration. The shock motion profiles are seen to follow a common trend in the shock acceleration–velocity frame, aside from an early time transient that is dependent on the initiating shock strength. The duration of the early time transient is seen to correlate with the initial shock strength. The common shock acceleration profile is seen to be Arrhenius-like with respect to the local particle velocity or pressure. A dual-rate pressure-dependent Arrhenius-type rate law is developed with the duration of the early rate set by the initial shock strength. The rate law is able to predict the shock motion for all tests well in both particle velocity and pressure space. In addition to directly measuring commonalities in the acceleration profiles of the experimental shock motion, this work provides insight into the functional form of the reaction rate laws for this TATB-based high explosive. The rate law also supports the concept that shock-driven reaction in heterogenous high explosives is driven by localized ignition and growth of hotspots.